Reciprocating pump



March 6, 1945. l c. c, s. LE c LAlR 21,371,054'

RECIPROCATING vPUMP Filed Nov. 5, 1943 2 Sheets-Sheet 2 55 1 o 1 Is s EJA B l /c- .-1 B

Patented Mar. 6, 1945 2,371,054 y RECHROCATING PUMP l Camille Clare Sprankllngr Le Clair, Acton',

London, England Applicaltlilon November 5, 1943, serial No. Great Britain October 28, 1942 8 Claims. (Cl. 103-37) This invention relates to for pumping fluids.

reciprocating pumps More particularly it relates to that type of pump comprising a cylinder, a piston and a plunger arranged in opposed relationship and reeiprccable in the cylinder, an inlet portin the cylinder adapted to be opened andclosed by the plunger, an outlet port in the cylinder adapted to be opened and closed by the piston, the movement of the piston in one direction being caused by the pressure of fluid entrapped in the cylinder between the piston and plunger while the latter. is carrying out its discharge stro-ke, the piston being subjected to the joint actions of a light spring and a heavy spring, both of which tend to force the piston towards the plunger, and the initial outward movement of the piston in a direction to uncover the outlet port due to the pressure imposed by the plunger on the iiuid entrapped in the cylinder between the plunger and the piston on the discharge stroke of the plunger being resisted by the light spring, which imposes a pressure on the piston only slightly in excess of the inlet pressure but suicient to maintain the piston in the desired initial position until diverted therefrom by the action of the plunger. In this type of pump the strength of the heavy spring is such that the spring imposes a pressure on the uid entrapped in the cylinder between the plunger and piston equal to, or greater than, the discharge pressure against which the pump is working, so that as soon as the piston uncovers the outlet port discharge of the fluid commences under the action of the heavy spring upon the piston, whereafter further outward movement of the piston ceases when a sucient area of the outlet port has been uncovered by the piston, the further discharge of the fluid from the cylinder being eected by the movement of the plunger approaching the piston.

One object of the present invention is to provide an improved pump of the type referred to above which is not only capable of pumping very small quantities of uid, but also in which the quantity'pumped can be metered with considerable accuracy, the pump having the further advantage that the amount pumped can be readily adjusted while the pump is running.

A further object is to provide a pump which is particularly adapted for pumping de-icing uids to de-icing apparatus on aircraft, or for central lubrication.

According to the present invention, a pump of the type referred to, wherein spring and the heavy spring are both I provide the light' arranged within a hollow member, which surrounds,v the outer end part of justably mounted upon the pump body, the said outer end part of the piston, the light spring and the heavy spring all being so arranged and supported within the hollow member that by adjusting the latter relatively to the pump body the output of the pump may be varied from a maximum to a minimum, and the arrangement being such that the output of the pump may be varied while the pump is running.

In one constructional form of the invention, the light spring is arranged to act between an abutment on the piston and a head member mounted upon the outer end of the piston and capable of limited relative axial movement thereon. The heavy spring is also arranged to act between the said head member and a cap member mounted on the pump body, the arrangement then being such that the initial movementl of the piston after the plunger has covered thel inlet port is resisted only by the loading of the light spring, which is compressed between the said abutment and the head member. Thus, very slight pressure is imposed initially upon the fluid entrapped between the plunger and piston until the plunger effectively seals the inlet port. The said cap member which is mounted upon the pump body is preferably adjustable towards and from the plunger, so that when it is adjusted in one or the other direction, the position of the piston relative to the inlet port is varied, whereby the pumping capacity can be adjusted from a maximum to a minimum, which may be nothing.

It is preferred to provide a locking device whereby the said cap member may be xed in any of its adjusted positions.

The plunger is also preferably spring-pressed outwardly and is conveniently reciprocated by rotatable means such as a cam or eccentric. It is also preferred to construct the cylinder in the form of a liner having a straight-through bore and fitted in a straight-through bore formed in the pump body.

It will be obvious that may be combined to form a, multiple pumping unit and that all the pump plungers may be operated by a common driving means such as a driving shaft provided with cams' or eccentrics. The pumps in such a multiple unit may be arranged in various ways such as, for example, in one straight line in which case there will be one cam or eccentric for each plunger, or two or more such rows may be arranged side by side with a driving shaft to each row or they may be in V the piston and which is ada number of such pumps l or opposed formation with two or more plungers operated by each cam or again they may be in radial formation with any number, such as six, eight or more, plungers per cam.

One constructional form of the present invention is shown, by way of example onthe accompanying drawings, whereon:

Fig. 1 is a sectional elevation of the pump;

Fig. 2 is an outside elevation of the pump; and

Fig. 3 is a view, partly in section, of a multiple pumping unit comprising two lines of pumps arranged on a common base in V-formation.

Referring to Figs. 1 and 2, for simplicity of description it will be assumed that the axis of the pump is arranged vertically, and the expressions upper and lower"will be used'in describing the construction and operation of the pump.

The pump comprises a body I formed with a parallel bore having both ends open. A liner or cylinder 2 is forced into the bore of the body and is formed with a parallel bore which is open at both ends. Inlet and outlet ports 3 and 4 diametrically opposed to each other in the lateral direction and spaced apart in the longitudinal, direction are formed in the cylinder wall and communicate respectively with an inlet passage 5 and an outlet duct 6 both formed in the pump body. The, inlet passage communicates with a source of supply of the liquid (which may be the hollow interior of the pump base) and the outlet duct 6 communicates with the pump outlet branch 1. A plunger 8 is slidably arranged in the lower part of the cylinder 2 and occupies substantially all the length of the bore from the inlet port 3 to the bottom end of the cylinder.

A piston 9 is also slidable in the upper part of.

the cylinder and occupies the length of the bore from the outlet port 4 to the top of the cylinder.

The plunger 8 projects out of the bottom end of the cylinder and is adapted to be actuated by a driven eccentric or cam Il! against which a headv on the plunger is held resiliently by a spring Il which bears against a shoulder on the cylinder and tends to force the plunger out of the bore. As described hereinafter, the piston is also spring-loaded by at least two springs, which act to force it downwards towards the plunger.

The arrangement is such that when the plunger 8 is in its most outward position in the cylinder bore as shown in Fig. 1, which is the position it occupies at the beginning of the discharge stroke, the upper end I2 of the plunger just fully uncovers the inlet port 3, thus permitting liquid to enter the bore via the passage 5 and port 3. When the plunger is in its innermost position in the cylinder bore, which is the position it occupies at the end of the discharge stroke, the inner end of the plunger is at a point somewhere within the width of the outlet port 4, such as at I3. The proportion of the area of the outlet port which will thus be covered by the plunger and the proportion of the area left uncovered will depend upon circumstances such as the speed and capacity of the pump, the viscosity of the liquid and so on. v

The piston 9 projects out of the top end of the cylinder bore into an enlarged bore in the body which is screw-threaded. Near its outer end the piston is formed with a shoulder I4 and is enclosed by a hollow head I5 into which is screwed a sleeve I6 loosely arranged on the pis ton below the shoulder. The head is formed with an external flange I1. A light spring I3 is fitted bottom end of lthe plug the whole adjustment from zero within the head I5 with one end bearing against the upper end of the head and the other end against the said shoulder I4. Thus, the piston is capable of small axial movement within the head I5. The spring I8 tends to force the piston 9 downwards towards the plunger 8 and the head I5 upwards, these movements being limited by the engagement of the shoulder I4 with a stop I9 formed by the upper end of the sleeve I6. The small axial outward movement of the piston within the head I5 is indicated by the clearance 20, this movement of the piston being limited by the end of the head I5. A hollow cap 2l is screwed into the said enlarged screwed bore of the pump body, the lower end of the cap being provided with an inwardly-projecting flange 22. The upper end of the bore of the cap is screwed to receive a hollow plug 23 wherein the upper end'of the head I5 is slidably arranged. A heavyspring' 24 is'arranged inside the cap around the head I5 with its upper end bearing against the 23 and its lower end against the external flange I1 which is formed around the lower end of the head. Thus, the head I5 is heavily loaded by the spring 24 which tends to force it downwards towards the plunger, this movement being limited by the contact of the flange I1 with a stop 25 formed by the upper face of the flange 22 on the cap.

To prevent pumping action taking place between any of these reciprocating parts ventilation is provided by a diagonal slot I5a cut in the top of the head, a hole or holes I1a cut in the lower flange I1 thereof and by a hole 2lb ydrilled in the hollow plug 23.

The complete assembly comprising the cap 2l, the plug 23, the head I5, the sleeve I6, the spring I8 and the heavy spring 24 is thus capable of being adjusted axially as a unit relative to the pump body and cylinder by rotating the cap on its screw thread. The purpose cf this adjustment is to vary the discharge of the pump, as will be explained later, and it is preferred that to full discharge should -be accomplished within one revolution of the cap. A locking' device is adapted to secure the cap in desired adjusted positions and an index device is provided to indicate such positions.

The locking device comprises a ilat spring 26 arranged in a slot 21 in the pump body and held therein by a screw 28 which passes through a hole formed in the spring at the lower end thereof and is screwed into a hole formed in the pump body.. 'Ihe inner end of the screw engages in a recess 29 formed in the cylinder 2, and thus acts to prevent the cylinder from becoming displaced. The free end 30 of the spring is curled inwards in the form of a circle which is adapted to engage in any one of a number of equidistantly-spaced slots 3| cut in the upper part 2 IA of the cap 2l.

Any number of slots 3l may be cut in the head 2IA but the preferred number is eleven. As shown in Fig. 2, they are numbered 0-10 and between the slot numbered 0 and the slot numbered 10 a small peg 32 is driven into the head. The top edge of the head is knurled as shown at 33 to form a finger grip.

The spring 26 is of such flexibility that its free end 30 can conveniently, say by the insertion of a scriber point, be deflected backwards to clear the numbered notches 3I thus permitting easy adjustment of the cap 2l.

The spring cannot, however, be readily bent backwards sufciently to clear the peg 32, which the can engages with slot No. 0, the piston 9 entirely covers the outlet port 4 and its lower end 84 is brought down to the upper edge of the inlet port 3 but does not cover any part thereof. When the cap is screwed out to its outermost position, in which the spring 28 engages the slot No. 10, see Figs. 1 and 2, the piston still the outlet port 4 but its lower end 34 now overruns it only suiilciently to ensure that a liquid tight seal is made as indicated by the line 34A.

The position of the piston (or the lower end thereof) as thus determined by the combined influences of the two springs (when expanded against their stops) and the adjusting meansv above described, i. e., the position the piston (or the lower end thereof) occupies at the commencement of the discharge stroke is hereinafter referred to as the initial position.

The operation of the pump is as follows: v

With the cap 2| adjusted to its outermost position (with the free end 30 of the spring' 28 in the slot No. 10. Figs. 1 and 2) and the inner end of the piston 9 in the initial position 34A, the plunger 8 commences to rise on its discharge stroke. Duringthe first part of the stroke, the plunger progressively covers the inlet port 3 and having done so entraps a charge of liquid between the plunger and the piston. As the plunger proceeds further on the instroke, it forces this charge o! liquid upwards, thereby also driving the piston upwards, rst against the resistance of the light spring I 8, until it (the piston) contacts the end of the head I5 and, thereafter, the piston and head against the resistance of the larger and heavier spring 24.

The resistance of the light spring |8 is only just suihcient to overcome such pressure as may be applied to the inlet, thereby enabling it to maintain the clearance space between itself and the head I5 and thus hold the' piston in the desired initial position against the pressure in the inlet. The spring I8, therefore, imposes only a very small pressure difference between the entrapped liquid and the inlet supply and since the movement permitted during the action of this spring before the heavy spring 24 comes into play, is suicient to enable the plunger 8 to cover the inlet port 3 thoroughly and make an ellective seal, it `follows that during the period when leakage of the liquid might take place, the pressure in the cylinder is kept low and the leakage thereby reduced to a negligible amount.

The resistance of the heavier spring 24, however, imposes a pressure in the pump cylinder equal to, or greater than, the discharge pressure against which the pump is working, so that as soon as the lower end 34A of the piston in its upward -movement reaches and uncovers the lower edge of the outlet port 4, discharge commences and, thereafter, as soon as sucient area of the outlet port has been uncovered the further upward movement of the piston ceases. Further discharge will then be effected by the movement'l of the plunger 8 approaching the piston and will be completed when the plunger and piston contact each other. This may occur before or when or after the plunger reaches theend of its inwith its stop 25) when a COVCIS descend together until 3 liquid from th'e stroke scinewherewlthm the width of the utlet portas aforesaid,l and when contact` occurs the clearance volume inthe cylinder is reduced to nil, thereby excludingl all liquid from the cylinder.

On thereturnl stroke the piston and plunger the former is arrested Ilrst by 1the contact of lthe ange I'I with the stop 25 and then the shouldery I4 with the stop I8. Itthen once more occupies its initial position. Thereafter, the plunger moves furtherdownwards leaving a voidbetween itself and the piston. As soon as theplunger uncovers the inlet port p inlet supply will flow into the pump cylinder under the inuence of atmospheric or suchother pressure as may be applied and ll thel void. Thereafter, the cycle of operations is repeated.

If the piston 9 together with its head I5, the springs I8 and 24, cap 2| and plug 23- are collectively adjusted downwards (towards the plunger), until the free end 30 of the locking spring 26 engages some intermediate slot 3| and y the bottom end of the piston occupies some intermediate initial position 35, the amount of liquid entrapped between the piston and plunger is less than before. Hence, the discharge of the pump is correspondingly less, but the same conditions of low pressureA difference between the pump cylinder and the inlet during the time the plunger is making an effective seal still obtain.

If the piston is adjusted downwards to its lower limit in which its lower end 34 coincides with of liquid entrapped between the pistonv and plunger is nil and the discharge of the pump is also nil. y

The output of the pump may therefore be modied from maximum to nil by a simple adjustment which can be performed while the pump 1s running.

With the type of locking device described above the convenient range of adjustment is limited one turn of the adjusting screw. It will be obvious, however, that when, for example, very ilne adjustments of output are required the-cap 2| may be provided with a finer thread 36 necessitating more than one complete revolution of the cap to eiect the total range of adjustment'.

It will be appreciated, that two or more pumps as described above can be combined into one multiple pumping unit. If a number of pumps is used, they may be mounted upon a base and arranged in any desired relationship to each other. For example, they may be arranged in `single line or in V-form or opposed or radially around the base. If arranged in line two or more such lines may be arranged parallel to each other on one base with two or more camshafts to opera-te them. In this case, the pumps of one line. may be staggered with relation to those of the adjacent line or lines.

When arranged in V, opposed or radial formation one cam may operate more than one pump.

One constructional form of such an arrangement the inlet and outlet passages 4l and 42 are shown carried through the jointing face between the pump and base in such a manner that the discharge pipe connections 43 are attached to the base. By this means it is not only possible to use a hollow base 38 as an inlet distributor, the hollow space in which the cams 40 or other driving mechanism run being filled with liquid to be pumped and the-inlet passages 5 of each -pump being connected thereto by the passages 44, but also it. makes it possible to remove and replace any pump without breaking its pipe connections.

It will however be appreciated that this construction is equally applicable where only a single pump is fitted.

In a modication the liquid supply may be kept separate from the main camshaft chamber in the hollow base, being introduced by a duct 45, which runs the full length of the base with branch ducts 46 leading to each individual pump.

The terms piston and plunger have been used above, and in the following claims, the more easily to identify these two members.

I claim:

1. A reciprocating pump, comprising a pump body having a cylinder formed therein, a piston and a plunger arranged in opposed relationship and reciprocable in said cylinder, an inlet port in the cylinder adapted to be opened and closed by said plunger, an outlet port in the cylinder adapted to be opened and closed by said piston, the movement of said piston in one direction being caused by the pressure of uid entrapped in said cylinder between said piston and said plunger while said plunger' is being moved through a discharge stroke, and a pair of unequally loaded springs biasing said piston toward said plunger, said springs being mounted within a hollow member surrounding the outer end portion of said piston, said hollow member being adjustably mounted on the pump body, the outer end portion of said piston and said springs being so arranged and supported within said hollow member than by adjusting said member relative to the pump body the output of the pump may be varied.

2. A reciprocating pump, comprising a pump body having a cylinder formed therein, a piston and a plunger arranged in opposed relationship and reciprocable in said cylinder, an inlet port in said cylinder adapted to be opened and closed by said plunger, an outlet port in said cylinder adapted to be opened and closed by said piston, the movement of said piston in 'one direction being caused by the pressure of' fluid entrapped in said cylinder between said piston and said plunger while said plunger is being moved through a discharge stroke, a head enclosing the outer end of said piston, a spring mounted between said head andsaid piston and resisting movement of said piston relative to said head, a hollow member enclosing said head and adjustably mounted on said pump body, and a second andheavier spring mounted between said hollow member and said head and biasing said head and said piston toward said plunger.

3. A reciprocating pump, comprising a pump body having a cylinder formed therein, a piston and a plunger arranged in opposed relationship and reciprocable in said cylinder, an inlet port in said cylinder adapted to be opened and closed by said plunger, an outlet port in said cylinder adapted to be opened and closed by said piston, the movement of said piston in one direction being caused by the pressure of fluid entrapped in said cylinder between said piston and said plunger while said through a discharge stroke, a head enclosing the outer end of said piston, a spring positioned between said head and a ange on said piston biasing said piston toward said plunger, an adjustable hollow member enclosing said head, a second and heavier spring mounted between said head and said hollow member biasing said head and said piston toward said plunger, and a pair of stop means limiting the extent of movement of said head and said piston under the influence of said springs.

4. The combination set forth in claim 3 in which said hollow member is adjustably mounted on said body whereby the Apumping end of said piston may have its position adjusted relative to said outlet port.

5. A reciprocating pump, comprising a pump body having a cylinder formed therein, a piston and a plunger arranged in opposed relationshipv and reciprocable in said cylinder, an inlet port in said cylinder adapted to be opened and. closed by said plunger, an outlet port in said cylinder adapted to be opened and closed by said piston, the movement of saidpiston in one direction being closed by the pressure of uid entrapped in said cylinder between said piston and said plunger while said plunger is being moved through a discharge stroke, a head enclosing the outer end of said piston and having an internal shoulder, a flange formed on said piston near its outer end, a spring enclosed in said head and restrained between said flange andthe inner end of said head, and spring biasing said flange l against said shoulder, a hollow member enclosing said head and adjustably mounted on said pump body, and a second and heavier spring positioned between said member and said head and biasing said piston toward said plunger.

6. The combination set forth in claim 5 wherein said second spring is held between a flange formed on said head and a shoulder in said hollow member. l

'7. The combination set forth in claim 2 wherein means are provided for locking said hollow member in its adjusted position.

8.v The combination set forth in claim 2 wherein said hollow member is provided with a plurality of external longitudinal circumferentially spaced slots, and a resilient member engages in a selected one of said slots, said resilient member being fixedly mounted relative to said pump body, whereby said hollow member may be locked in an adjusted position.

CAMILLE CLARE SPRANKLING LE CLAIR..

plunger 1s being moved 

